first (1st) rib (anatomy)
Last reviewed 01/2018
The first rib is the most superior within the thoracic cavity. It is atypical in structure:
- head:
- single articular facet for synovial joint with upper hemifacet on lateral body of T1
- relatively small
- reinforced by typical radiate ligament
- neck:
- slopes superiorly and slightly posteriorly to join the shaft
- relations:
- anterior ramus of eighth cervical nerve on superior surface
- anterior ramus of first thoracic nerve on inferior surface
- posterior to anterior on thoracic surface: stellate ganglion or sympathetic chain, supreme intercostal vein, superior intercostal artery. These structures are in contact with the apposing cervical pleura.
- tubercle:
- in anatomical position, most posterior point of rib
- medial facet for synovial joint articulation with first thoracic vertebra transverse process
- laterally provides attachment for;
- lateral costotransverse ligament
- costalis muscle
- longissimus muscle
- angle: there is no angle as it has effectively fused with the tubercle
- shaft: see submenu
- general points:
- the first rib is bent into a very tight curve to turn 180 degrees from vertebra to sternum
- in the anatomical position, the rib is inclined 45 degrees to the horizontal